1. Field of the Invention
The present invention relates to a pharmaceutical composition which can be employed as an essential therapeutic agent for dermal disease caused by damage of a skin barrier, such as atopic dermatitis, and specifically, it concerns a composition which repair a damaged skin barrier to a normal condition so as to recover the skin's properties of moisture-retaining capacity and selective permeability, thereby maximizing inhibition or alleviation of skin irritation due to external irritants. More particularly, the invention relates to a therapeutic composition for a broad spectrum of skin diseases, comprising sphingolipid long-chain base selected from the group consisting of phytosphingosine, acetylphytosphingosine, tetraacetyl phytosphingosine, hexanoylphytosphingosine and acetylphytosphingosine phosphate, andlysophosphatidic acid selected from the group consisting of lyso-stearoyl phosphatidic acid (18:0), lyso-oleoyl phosphatidic acid (18:1), lyso-palmitoyl phosphatidic acid (16:0) and natural lyso-phosphatidic acid derived from egg yolk or beans, with respect to the total weight of the composition.
2. Description of the Related Art
Many skin diseases such as psoriasis and atopic dermatitis are known to be diseases which are hard to cure, like cancers, AIDS and dementia, and thereby plague the human race. The reasons for these diseases are still not clearly understood, and a fundamental therapy is not yet developed. It is believed that a combination of multiple factors including genetic, environmental and immunological causes, may cause skin diseases. Such diseases have characteristics of chronic and periodic onset and recurrence.
Although most skin diseases are not fatal, many patients experience severe hindrance in managing daily lives, and especially, juveniles including children have difficulties in doing school work, due to emotional upset and loss of concentration, causing social problems. Regarding atopic dermatitis, it was reported that 85 percent of patients became ill before the age of 5, and 60% of the patients still have symptoms of atopic dermatitis when they reach adulthood. Though it is known that on average, 5 to 10% of the total population experiences this disease, and the incidence is increasing due to environmental causes. One study found that the number of such patients in the United States increased by three times since the 1970s. In the world, Korea belongs to a group of nations whose incidence of patients with atopic dermatitis is high. The reason for this is thought to be the trend that apartments are becoming the primary accommodation. According to a survey of the United States, 56% of the respondents said they feel uncomfortable in their social lives, and 80% suffer sleep difficulties.
So far, there is no perfect cure for atopic dermatitis. Some antibiotics have been used for the treatment of skin infections which often accompany atopic dermatitis, depending on the progress of the lesions. UV radiation or immunosuppressants can also be applied to the patients with severe lesions. Such treatments are based on the knowledge that abnormal functioning of macrophages and T cells is a main factor of atopic dermatitis, and overproduction of IL-4 and IL-5 in the skin tissues of the lesions are closely related to high concentrations of IgE and eosinophilia which are characteristics of atopic dermatitis (Ohmen J D et al., J Immunol., 154: 1956-1963, 1995-Overproduction of IL-10; Hamid Q et al., J Clin. Invest., 94: 870-876, 1994-Cytokine expression; which are incorporated by reference herein in their entireties).
Steroid-containing ointments or anti-histamine agents have been used, but are only a partial cure, and have considerable side effects. Dermatologists warn patients about side effects caused by long-term steroid therapy, and it is observed that termination of the application of steroids is often followed by lesion recurrence. Steroids for external or oral application make the skin layers thin or cause osteoporosis and inhibit growth in children, upon long-term use. Therefore, much research conducted so far focuses on development of steroid substances with fewer side effects. Studies on non-steroid or low steroid preparations were presented at the American Academy of Dermatology Annual Conference in 2000, thus being a recent trend.
Considering the above, what is needed is a composition for dermatological application which is effective in treating skin disorders, yet has fewer side effects that the above described treatments.